Integrated circuits are formed on semiconductor wafers. The wafers are sawed into dies, which are packaged before being used. The recent trend shows that the thickness of the wafers became increasing thinner. With thinner wafers, three Dimensional Integrated Circuit (3DIC) formation processes can be accommodated.
The thinned wafers resulted in the difficulty in the integrated circuit manufacturing processes. An example is that the thin wafers have significant warpage, and some of the processes may not be able to be performed on the warped wafers. To solve this problem, when thin wafers are handled or wafers are thinned, carriers are bonded to the thin wafers. The carriers are thick enough, and do not suffer from the warpage problem. Through adhesives, thin wafers that are adhered on carriers may remain planar.
The warpage of the thin wafers, however, is rejuvenated whenever the thinner wafers are demounted from the carriers. To solve this problem, the thin wafers may be diced into dies along with the carriers. Since the dies have small sizes, the warpage problem in the resulting dies is not significant. A problem in this solution is that the carriers are also diced, and hence cannot be reused.